Aromatic amine derivative and organic electroluminescent element employing the same

ABSTRACT

The present invention relates to aromatic amine derivatives having a specific structure in which a substituted anthracene structure is bonded to an amine structure substituted with benzene rings having substituent groups; and organic electroluminescence devices comprising a cathode, an anode and one or plural organic thin film layers having at least a light emitting layer which are sandwiched between the cathode and the anode wherein at least one of the organic thin film layers contains the above aromatic amine derivative in the form of a single substance or a component of a mixture. There are provided organic electroluminescence devices having a high luminance of light emitted and a high efficiency of blue light emission and exhibiting a long life, as well as novel aromatic amine derivatives capable of realizing such organic electroluminescence devices.

TECHNICAL FIELD

The present invention relates to novel aromatic amine derivatives andorganic electroluminescence devices using the same, and moreparticularly to organic electroluminescence devices which exhibit a highluminance of light emitted and a high efficiency of light emission andhave a long life, and novel aromatic amine derivatives capable ofrealizing such organic electroluminescence devices.

BACKGROUND ART

The organic electroluminescence devices (organic EL devices) arespontaneous light emitting devices which utilize the principle that afluorescent substance emits light by energy of recombination betweenholes injected from an anode and electrons injected from a cathode uponapplication of an electric field thereto.

Since C. W. Tang, et al., of Eastman Kodak Company have reported organicEL devices of a laminate type driven at a low electric voltage (C. W.Tang and S. A. Vanslyke, “Applied Physics Letters”, Vol. 51, p. 913,1987, etc.), many studies have been intensely conducted on organic ELdevices made of organic materials.

The organic EL devices reported by Tang, et al., have such a laminatestructure including a light emitting layer made oftris(8-hydroxyquinolinol)aluminum and a hole transport layer made of atriphenyl diamine derivative. The laminate structure of these deviceshas advantages such as increased efficiency of hole injection into thelight emitting layer, increased efficiency of production of excitedparticles (excitons) which are produced by blocking electrons injectedfrom a cathode and recombining the electrons with holes, and confinementof the excitons produced within the light emitting layer. As thestructure of such organic EL devices, there are well known a two-layerstructure including a hole transporting (injecting) layer and anelectron transporting and light emitting layer, a three-layer structureincluding a hole transporting (injecting) layer, a light emitting layerand an electron transporting (injecting) layer, etc. In these organic ELdevices of a laminate type, various structures and production methodsthereof have been proposed in order to enhance an efficiency ofrecombination between holes and electrons injected thereinto.

As the light emitting materials for the organic EL devices, there areknown chelate complexes such as tris(8-quinolinolato)aluminum complexes,coumarin derivatives, tetraphenyl butadiene derivatives, bis-styrylarylene derivatives and oxadiazole derivatives. It has been reportedthat these light emitting materials emit blue to red light in a visiblerange, and it is therefore expected to realize color display devices byusing these light emitting materials (for example, refer to JP8-239655A, JP 7-138561A and JP 3-200289A, etc.).

In addition, JP 2001-207167A discloses the devices using aminoanthracenederivatives as a green light emitting material. However, the lightemitting material has failed to provide devices having a long life and ahigh efficiency of light emission and, therefore, has been practicallyunusable.

In recent years, although many organic EL devices having a highluminance and a long life have been disclosed or reported, theperformance thereof has been still unsatisfactory. Therefore, is hasbeen strongly demanded to develop materials for organic EL deviceshaving a more excellent efficiency of light emission.

DISCLOSURE OF THE INVENTION

The present invention has been made to solve the above problems. Anobject of the present invention is to provide organic EL devices whichexhibit a high luminance of light emitted and a high efficiency of lightemission and have a long life, and novel aromatic amine derivativescapable of realizing such organic EL devices.

As a result of extensive researches for developing materials for organicEL devices having the above advantageous properties as well as organicEL devices using such materials, the inventors have found that the aboveobject can be achieved by using aromatic amine derivatives representedby the following general formula (1) in which a substituted anthracenestructure is bonded to an amine structure substituted with benzene ringshaving substituent groups. The present invention has been accomplishedon the basis of the above finding.

Thus, the present invention provides:

An aromatic amine derivative represented by the following generalformula (1):

wherein A¹ and A² are each independently a hydrogen atom, a substitutedor unsubstituted alkyl group having 1 to 10 carbon atoms, a substitutedor unsubstituted aryl group having 5 to 50 nuclear carbon atoms, asubstituted or unsubstituted cycloalkyl group having 3 to 20 nuclearcarbon atoms, a substituted or unsubstituted alkoxy group having 1 to 10carbon atoms, a substituted or unsubstituted aryloxy group having 5 to50 nuclear carbon atoms, a substituted or unsubstituted arylamino grouphaving 5 to 50 nuclear carbon atoms, a substituted or unsubstitutedalkylamino group having 1 to 10 carbon atoms, or a halogen atom; p and qare each an integer of 1 to 5 and s is an integer of 1 to 9 wherein whenp or q is 2 or more, a plurality of A¹ or A² groups may be the same ordifferent and may be bonded to each other to form an saturated orunsaturated ring, with the proviso that both of A¹ and A² are notsimultaneously hydrogen atoms;

R¹ is a substituted or unsubstituted secondary or tertiary alkyl grouphaving 3 to 10 carbon atoms, or a substituted or unsubstituted secondaryor tertiary cycloalkyl group having 3 to 10 carbon atoms; t is aninteger of 1 to 9, and when t is 2 or more, a plurality of R¹ groups maybe the same or different;

R² is a hydrogen atom, a substituted or unsubstituted alkyl group having1 to 10 carbon atoms, a substituted or unsubstituted aryl group havingto 50 nuclear carbon atoms, a substituted or unsubstituted cycloalkylgroup having 3 to 20 nuclear carbon atoms, a substituted orunsubstituted alkoxy group having 1 to 10 carbon atoms, a substituted orunsubstituted aryloxy group having 5 to 50 nuclear carbon atoms, asubstituted or unsubstituted arylamino group having 5 to 50 nuclearcarbon atoms, a substituted or unsubstituted alkylamino group having 1to 10 carbon atoms, or a halogen atom; u is an integer of 0 to 8 andwhen u is 2 or more, a plurality of R² groups may be the same ordifferent; and

a sum of s, t and u (s+t+u) is an integer of 2 to 10.

Also, the present invention provides:

An organic electroluminescence device comprising a cathode, an anode andone or plural organic thin film layers having at least a light emittinglayer which are sandwiched between the cathode and the anode, wherein atleast one of the organic thin film layers contains the above aromaticamine derivative in the form of a single substance or a component of amixture. The light emitting layer preferably contains the aromatic aminederivative in the form of a single substance or a component of amixture.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a view showing NMR spectrum of the compound (6) as an exampleof the aromatic amine derivatives of the present invention.

FIG. 2 is a view showing NMR spectrum of the compound (7) as an exampleof the aromatic amine derivatives of the present invention.

FIG. 3 is a view showing NMR spectrum of the compound (8) as an exampleof the aromatic amine derivatives of the present invention.

FIG. 4 is a view showing NMR spectrum of the compound (9) as an exampleof the aromatic amine derivatives of the present invention.

FIG. 5 is a view showing NMR spectrum of the compound (10) as an exampleof the aromatic amine derivatives of the present invention.

FIG. 6 is a view showing NMR spectrum of the compound (11) as an exampleof the aromatic amine derivatives of the present invention.

BEST MODE FOR CARRYING OUT THE INVENTION

The novel aromatic amine derivatives of the present invention arerepresented by the following general formula (1):

In the general formula (1), A¹ and A² are each independently a hydrogenatom; a substituted or unsubstituted alkyl group having 1 to 10 carbonatoms and preferably 1 to 6 carbon atoms; a substituted or unsubstitutedaryl group having 5 to 50 nuclear carbon atoms and preferably 5 to 10nuclear carbon atoms; a substituted or unsubstituted cycloalkyl grouphaving 3 to 20 nuclear carbon atoms and preferably 5 to 10 nuclearcarbon atoms; a substituted or unsubstituted alkoxy group having 1 to 10carbon atoms and preferably 1 to 6 carbon atoms; a substituted orunsubstituted aryloxy group having 5 to 50 nuclear carbon atoms andpreferably 5 to 10 nuclear carbon atoms; a substituted or unsubstitutedarylamino group having 5 to 50 nuclear carbon atoms and preferably 5 to20 nuclear carbon atoms; a substituted or unsubstituted alkylamino grouphaving 1 to 10 carbon atoms and preferably 1 to 6 carbon atoms; or ahalogen atom.

Examples of the substituted or unsubstituted alkyl group as A¹ and A²include methyl, ethyl, propyl, isopropyl, butyl, sec-butyl, tert-butyl,pentyl, hexyl, heptyl, octyl, stearyl, 2-phenylisopropyl,trichloromethyl, trifluoromethyl, benzyl, α-phenoxybenzyl,α,α-dimethylbenzyl, α,α-methylphenylbenzyl, α,α-ditrifluoromethylbenzyl,triphneylmethyl and α-benzyloxybenzyl.

Examples of the substituted or unsubstituted aryl group as A¹ and A²include phenyl, 2-methylphenyl, 3-methylphenyl, 4-methylphenyl,4-ethylphenyl, biphenyl, 4-methyl biphenyl, 4-ethyl biphenyl,4-cyclohexyl biphenyl, terphenyl, 3,5-dichlorophenyl, naphthyl, 5-methylnaphthyl, anthryl and pyrenyl.

Examples of the substituted or unsubstituted cycloalkyl group as A¹ andA² include cyclopropyl, cyclobutyl, cyclopentyl, cyclohexyl, norbornyland adamantyl.

Examples of the substituted or unsubstituted alkoxy group as A¹ and A²include methoxy, ethoxy, propoxy, isopropoxy, butoxy, isobutoxy,sec-butoxy, tert-butoxy, various pentyloxy groups and various hexyloxygroups.

Examples of the substituted or unsubstituted aryloxy group as A¹ and A²include phenoxy, tolyloxy and naphthyloxy.

Examples of the substituted or unsubstituted arylamino group as A¹ andA² include diphenylamino, ditolylamino, dinaphthylamino andnaphthylphenylamino.

Examples of the substituted or unsubstituted alkylamino group as A¹ andA² include dimethylamino, diethylamino and dihexylamino.

Examples of the halogen atom as A¹ and A² include a fluorine atom, achlorine atom, a bromine atom, etc.

However, in the general formula (1), both of A¹ and A² are notsimultaneously hydrogen atoms.

In the general formula (1), A¹ is preferably a secondary or tertiaryalkyl group or a secondary or tertiary cycloalkyl group, and morepreferably a secondary alkyl group or a secondary cycloalkyl group, andA² is preferably a primary or secondary alkyl group, and more preferablymethyl, ethyl, propyl, isopropyl, butyl, sec-butyl or tert-butyl.

In the general formula (1), p and q are each an integer of 1 to 5 andpreferably 1 to 3. More preferably, p is 1 and q is 1 or 2.

When p or q is 2 or more, a plurality of A¹ or A² groups may be the sameor different and may be bonded to each other to form an saturated orunsaturated ring.

Also, s is an integer of 1 to 9 and preferably 1 to 3.

R¹ is a substituted or unsubstituted secondary or tertiary alkyl grouphaving 3 to 10 carbon atoms, or a substituted or unsubstituted secondaryor tertiary cycloalkyl group having 3 to 10 carbon atoms.

Examples of the substituted or unsubstituted secondary or tertiary alkylgroup as R¹ include isopropyl, tert-butyl, sec-butyl, tert-pentyl,1-methylbutyl, 1-methylpentyl, 1,1′-dimethylpentyl, 1,1′-diethylpropyl,1-benzyl-2-phenylethyl, 1-methoxyethyl and 1-phenyl-1-methylethyl.

Examples of the substituted or unsubstituted secondary or tertiarycycloalkyl group as R¹ include cyclopentyl, norbornyl and adamantyl.

In the general formula (1), R¹ is preferably a tertiary alkyl group or asecondary cycloalkyl group, more preferably tert-butyl or cyclohexyl,and most preferably cyclohexyl.

In the general formula (1), t is an integer of 1 to 9 and preferably 1to 3. When t is 2 or more, a plurality of R¹ groups may be the same ordifferent.

R² is a hydrogen atom, a substituted or unsubstituted alkyl group having1 to 10 carbon atoms and preferably 1 to 6 carbon atoms; a substitutedor unsubstituted aryl group having 5 to 50 nuclear carbon atoms andpreferably 5 to 10 nuclear carbon atoms; a substituted or unsubstitutedcycloalkyl group having 3 to 20 nuclear carbon atoms and preferably 5 to10 nuclear carbon atoms; a substituted or unsubstituted alkoxy grouphaving 1 to 10 carbon atoms and preferably 1 to 6 carbon atoms; asubstituted or unsubstituted aryloxy group having 5 to 50 nuclear carbonatoms and preferably 5 to 10 nuclear carbon atoms; a substituted orunsubstituted arylamino group having 5 to 50 nuclear carbon atoms andpreferably 5 to 20 nuclear carbon atoms; a substituted or unsubstitutedalkylamino group having 1 to 10 carbon atoms and preferably 1 to 6carbon atoms; or a halogen atom.

Specific examples of the substituted or unsubstituted alkyl, aryl,cycloalkyl, alkoxy, aryloxy, arylamino and alkylamino groups as well asthe halogen atom as R² include the same groups as those exemplified asA¹ and A² above.

In the general formula (1), R² is preferably a tertiary alkyl group or asecondary cycloalkyl group, more preferably tert-butyl or cyclohexyl,and most preferably cyclohexyl.

In the general formula (1), u is an integer of 0 to 8 and preferably 0to 2. When u is 2 or more, a plurality of R² groups may be the same ordifferent.

Also, in the general formula (1), a sum of s, t and u (s+t+u) is aninteger of 2 to 10 and preferably 2 to 6.

Further, the aromatic amine derivatives having the structure representedby the general formula (1) according to the present invention arepreferably any of the compounds represented by the following generalformulae (2), (2-1) to (2-3) and (3) to (5):

In the general formulae (2), (2-1) to (2-3) and (3) to (5), A¹, A², p,q, R¹ and R² are the same as defined above. Also, R³ and R⁴ arerespectively the same as R², and examples of the preferred R³ and R⁴ arealso the same as those of R².

Specific examples of the aromatic amine derivatives represented by thegeneral formulae (1) as well as (2), (2-1) to (2-3) and (3) to (5)include compounds (1) to (65) enumerated below, though not particularlylimited thereto. Meanwhile, in the following compounds, Me represents amethyl group.

In the aromatic amine derivatives represented by the general formula (1)according to the present invention, since the substituted anthracenestructure is bonded to the amine structure substituted with benzenerings having substituent groups, the association between the compoundsis prevented, resulting in a prolonged life thereof. In addition, sincethe anthracene skeleton has bulky substituent groups such as secondaryor tertiary alkyl or cycloalkyl groups, the anthracene structureexhibits a large steric repulsion against the amine structure, so thatproperties of these compounds such as life can be further improved.Further, the aromatic amine derivatives have a strong fluorescence in asolid state, and are excellent in field light emission, which leads to afluorescent quantum efficiency as high as 0.3 or more. In addition, thearomatic amine derivatives of the present invention exhibit not onlyexcellent capabilities of injecting holes from the metal electrode ororganic thin film layers and transporting the holes, but also excellentcapabilities of injecting electrons from the metal electrode or organicthin film layers and transporting the electrons, and are, therefore,usefully usable as light emitting materials for organic EL devices.Besides, the aromatic amine derivatives of the present invention may beused together with other hole transporting materials, electrontransporting materials or doping materials.

The organic EL device of the present invention includes an anode, acathode, and one or plural organic thin film layers. In the case of onelayer type, a light emitting layer as the organic thin film layer isprovided between the anode and cathode. The light emitting layercontains a light emitting material and may further contain a holeinjecting material or an electron injecting material in order toeffectively transport holes injected from the anode or electronsinjected from the cathode to the light emitting material. The aromaticamine derivatives represented by the general formula (1) have a highlight emitting property and excellent hole injectability and holetransportability as well as excellent electron injectability andelectron transportability and, therefore, can be used as a lightemitting material in the light emitting layer.

In the organic EL device of the present invention, the light emittinglayer contains the material for organic EL devices according to thepresent invention in an amount of preferably 0.1 to 20% by weight andmore preferably 1 to 10% by weight. Further, the material for organic ELdevices according to the present invention exhibits not only anextremely high fluorescent quantum efficiency but also high holetransportability and electron transportability, and further are capableof forming a uniform thin film. Therefore, the light emitting layer maybe formed from only the light emitting material of the presentinvention.

Examples of the organic EL device of a multilayer type include thosehaving multilayer structures such as (an anode/a hole injecting layer/alight emitting layer/a cathode), (an anode/a light emitting layer/anelectron injecting layer/a cathode) and (an anode/a hole injectinglayer/a light emitting layer/an electron injecting layer/a cathode).

The light emitting layer may also optionally contain, in addition to thecompound represented by the general formula (1) according to the presentinvention, conventionally known materials such as light emittingmaterials, doping materials, hole injecting materials and electroninjecting materials according to requirements. The organic EL devicehaving such a multilayer structure can be prevented from suffering fromdeterioration in luminance and service life due to quenching. Ifrequired, the light emitting materials, doping materials, hole injectingmaterials and electron injecting materials may be used in combinationwith each other. The use of the doping materials enables the resultantdevice to be improved in luminance of light emitted and efficiency oflight emission, and further emit a red color light or a blue colorlight. Further, in the organic EL device of the present invention, thehole injecting layer, the light emitting layer and the electroninjecting layer may respectively have a multilayer structure includingtwo or more layers. In this case, the multi-layer hole injecting layermay include a hole injecting layer into which holes are injected fromthe electrode, and a hole transporting layer for accepting the holesfrom the hole injecting layer and transporting the holes to the lightemitting layer. Also, the multi-layer electron injecting layer mayinclude an electron injecting layer into which electrons are injectedfrom the electrode, and an electron transporting layer for accepting theelectrons from the electron injecting layer and transporting theelectrons to the light emitting layer. These respective layers may beselectively used according to various factors such as energy level ofthe materials used, heat resistance, and adhesion to the organic thinfilm layers or the metal electrodes.

Examples of the light emitting materials or doping materials that areusable in the light emitting layer together with the compoundrepresented by the general formula (1) include anthracene, naphthalene,phenanthrene, pyrene, tetracene, coronene, chrysene, fluorescein,perylene, phthaloperylene, naphthaloperylene, perynone, phthaloperynone,naphthaloperynone, diphenyl butadiene, tetraphenyl butadiene, coumarin,oxadiazole, aldazine, bisbenzoxazoline, bisstyryl, pyrazine,cyclopentadiene, quinoline metal complexes, aminoquinoline metalcomplexes, benzoquinoline metal complexes, imines, diphenyl ethylene,vinyl anthracene, diaminocarbazole, pyran, thiopyran, polymethine,merocyanine, imidazole-chelated oxinoid compounds, quinacridone, rubreneand fluorescent dyes, though not particularly limited thereto.

The hole injecting material is preferably made of compounds which have agood hole transportability as well as excellent capabilities ofaccepting holes injected from the anode and injecting the holes into thelight emitting layer or light emitting material, prevent excitedparticles (excitons) produced in the light emitting layer from movinginto the electron injecting layer or electron injecting material, andexhibit an excellent capability of forming a thin film. Specificexamples of the hole injecting material include phthalocyaninederivatives, naphthalocyanine derivatives, porphyrin derivatives,oxazole, oxadiazole, triazole, imidazole, imidazolone, imidazole thione,pyrazoline, pyrazolone, tetrahydroimidazole, hydrazone, acyl hydrazone,polyaryl alkanes, stilbene, butadiene, benzidine-type triphenyl amine,styryl amine-type triphenyl amine, diamine-type triphenyl amine andderivatives thereof, as well as polyvinyl carbazoles, polysilanes, andhigh molecular materials such as conductive polymers, though notparticularly limited thereto.

Of these hole injecting materials usable in the organic EL device of thepresent invention, more effective hole injecting materials are aromatictertiary amine derivatives and phthalocyanine derivatives.

Specific examples of the aromatic tertiary amine derivatives includetriphenyl amine, tritolyl amine, tolyldiphenyl amine,N,N′-diphenyl-N,N′-(3-methylphenyl)-1,1′-biphenyl-4,4′-diamine,N,N,N′,N′-(4-methylphenyl)-1,1′-phenyl-4,4′-diamine,N,N,N′,N′-(4-methylphenyl)-1,1′-biphenyl-4,4′-diamine,N,N′-diphenyl-N,N′-dinaphthyl-1,1′-biphenyl-4,4′-diamine,N,N′-(methylphenyl)-N,N′-(4-n-butylphenyl)-phenanthrene-9,10-diamine,N,N-bis(4-di-4-tolylaminophenyl)-4-phenyl cylcohexane, and oligomers andpolymers having these aromatic tertiary amine skeletons, though notparticularly limited thereto.

Specific examples of the phthalocyanine (Pc) derivatives includephthalocyanine derivatives such as H₂Pc, CuPc, CoPc, NiPc, ZnPc, PdPc,FePc, MnPc, ClAlPc, ClGaPc, ClInPc, ClSnPc, Cl₂SiPc, (HO)AlPc, (HO)GaPc,VOPc, TiOPc, MoOPc and GaPc-O-GaPc, as well as naphthalocyaninederivatives, though not particularly limited thereto.

Also, in the organic EL device of the present invention, a layercontaining these aromatic tertiary amine derivatives and/orphthalocyanine derivatives, for example, as the above hole transportinglayer or hole injecting layer, is preferably provided between the lightemitting layer and the anode.

The electron injecting material is preferably made of compounds whichhave a good electron transportability as well as excellent capabilitiesof accepting electrons injected from the cathode and injecting theelectrons into the light emitting layer or light emitting material,prevent excited particles produced in the light emitting layer frommoving into the hole injecting layer, and exhibit an excellentcapability of forming a thin film. Specific examples of the electroninjecting material include fluorenone, anthraquinodimethane,diphenoquinone, thiopyran dioxide, oxazole, oxadiazole, triazole,imidazole, perylenetetracarboxylic acid, fluorenylidene methane,anthrone, and derivatives thereof, though not particularly limitedthereto. Further, an electron accepting substance and an electrondonating substance may be added to the hole injecting material and theelectron injecting material, respectively, for enhancing a sensitizationthereof.

In the organic EL device of the present invention, among these electroninjecting materials, more effective electron injecting materials aremetal complex compounds and nitrogen-containing five-membered ringderivatives.

Specific examples of the metal complex compounds include8-hydroxyquinolinato lithium, bis(8-hydroxyquinolinato) zinc,bis(8-hydroxyquinolinato) copper, bis(8-hydroxyquinolinato) manganese,tris(8-hydroxyquinolinato) aluminum, tris(2-methyl-8-hydroxyquinolinato)aluminum, tris(8-hydroxyquinolinato) gallium,bis(10-hydroxybenzo[h]quinolinato) beryllium,bis(10-hydroxybenzo[h]quinolinato) zinc, bis(2-methyl-8-quinolinato)chlorogallium, bis(2-methyl-8-quinolinato) (o-cresolato) gallium,bis(2-methyl-8-quinolinato) (1-naphtholato) aluminum, andbis(2-methyl-8-quinolinato) (2-naphtholato) gallium, though notparticularly limited thereto.

The preferred nitrogen-containing five membered ring derivatives are,for example, derivatives of oxazole, thiazole, oxadiazole, thiadiazoleor triazole. Specific examples of the nitrogen-containing five memberedring derivatives include 2,5-bis(1-phenyl)-1,3,4-oxazole, dimethylPOPOP, 2,5-bis(1-phenyl)-1,3,4-thiazole,2,5-bis(1-phenyl)-1,3,4-oxadiazole,2-(4′-tert-butylphenyl)-5-(4″-biphenyl)-1,3,4-oxadiazole,2,5-bis(1-naphthyl)-1,3,4-oxadiazole,1,4-bis[2-(5-phenyloxadiazolyl)]benzene,1,4-bis[2-(5-phenyloxadiazolyl)-4-tert-butylbenzene],2-(4′-tert-butylphenyl)-5-(4″-biphenyl)-1,3,4-thiadiazole,2,5-bis(1-naphthyl)-1,3,4-thiadiazole,1,4-bis[2-(5-phenylthiadiazolyl)]benzene,2-(4′-tert-butylphenyl)-5-(4″-biphenyl)-1,3,4-triazole,2,5-bis(1-naphthyl)-1,3,4-triazole, and1,4-bis[2-(5-phenyltriazolyl)]benzene, though not particularly limitedthereto.

In the organic EL device of the present invention, the light emittinglayer may also optionally contain, in addition to the compoundrepresented by the general formula (1), at least one material selectedfrom the group consisting of light emitting materials, doping materials,hole injecting materials and electron injecting materials. The organicEL device of the present invention may be further provided on a surfacethereof with a protective layer, or the whole part thereof may beprotected with silicone oil, resins, etc., in order to enhance astability thereof against temperature, humidity, atmosphere, etc.

The anode of the organic EL device according to the present inventionmay be suitably made of a conductive material having a work functionmore than 4 eV. Examples of the conductive material for the anodeinclude carbon, aluminum, vanadium, iron, cobalt, nickel, tungsten,silver, gold, platinum, palladium and alloys thereof, metal oxides suchas tin oxide and indium oxide which are used for ITO substrates or NESAsubstrates, and organic conductive resins such as polythiophene andpolypyrrole. The cathode of the organic EL device according to thepresent invention may be suitably made of a conductive material having awork function of 4 eV or less. Examples of the conductive material forthe cathode include magnesium, calcium, tin, lead, titanium, yttrium,lithium, ruthenium, manganese, aluminum, lithium fluoride and alloysthereof, though not particularly limited thereto. Typical examples ofthe alloys include alloys of magnesium and silver, alloys of magnesiumand indium, and alloys of lithium and aluminum, though not particularlylimited thereto. The ratio between the constituting metals in the alloysmay be controlled and appropriately determined depending upontemperature of vapor deposition sources, atmosphere, vacuum degree, etc.The anode and cathode may be constituted of two or more layers, ifrequired.

At least one surface of the organic EL device of the present inventionpreferably exhibits a sufficient transparency in a wavelength range oflight emitted therefrom in order to enhance an efficiency of lightemission thereof. Further, the substrate used in the device is alsopreferably transparent. The transparent electrode is formed from theabove conductive material by vapor deposition method, sputtering method,etc., so as to ensure a desirable transparency thereof. The electrodedisposed on a light emitting surface of the device preferably has alight transmittance of 10% or more. The substrate is not particularlylimited as long as it has a good mechanical and thermal strength as wellas a good transparency. Examples of the substrate include glasssubstrates and transparent resin films. Specific examples of thetransparent resin films include films made of polyethylene,ethylene-vinyl acetate copolymer, ethylene-vinyl alcohol copolymer,polypropylene, polystyrene, polymethyl methacrylate, polyvinyl chloride,polyvinyl alcohol, polyvinyl butyral, nylons, polyether ether ketones,polysulfones, polyether sulfones,tetrafluoroethylene-perfluoroalkylvinyl ether copolymer, polyvinylfluoride, tetrafluoroethylene-ethylene copolymer,tetrafluororethylene-hexafluoropropylene copolymer,polychlorotrifluoroethylene, polyvinylidene fluoride, polyesters,polycarbonates, polyurethanes, polyimides, and polyether imides.

The respective layers of the organic EL device of the present inventionmay be formed by either a dry film-forming method such as vacuumdeposition, sputtering, plasma and ion-plating, or a wet film-formingmethod such as spin-coating, dipping and flow-coating. The thickness ofthe respective layers is not particularly limited, but should beadjusted to an appropriate range. If the thickness is too large, a largeelectric voltage must be applied to the device in order to achieve adesired light output, resulting in a poor efficiency of light emission.On the other hand, if the thickness is too small, pinholes tend to beformed in the layers, thereby failing to obtain a sufficient luminanceof light emitted even upon applying an electric field thereto. Thesuitable thickness of the respective layers is usually in the range offrom 5 nm to 10 μm and preferably from 10 nm to 0.2 μm.

In the wet film-forming method, materials constituting the respectivelayers are dissolved or dispersed in a suitable solvent such as ethanol,chloroform, tetrahydrofuran and dioxane to form a thin film thereof. Thesolvent used for forming the respective layers is not particularlylimited. Also, suitable resins or additives may be added to therespective organic thin film layers for the purposes of improving afilm-forming property, preventing formation of pinholes in the resultantfilm, etc. Examples of the resins usable for the above purposes includeinsulating resins such as polystyrene, polycarbonates, polyarylates,polyesters, polyamides, polyurethanes, polysulfones, polymethylmethacrylate, polymethyl acrylate and celluloses as well as copolymersthereof, photoconductive resins such as poly-N-vinyl carbazole andpolysilanes, and conductive resins such as polythiophene andpolypyrrole. Examples of the additives include antioxidants, ultravioletabsorbers and plasticizers.

As described above, by using the aromatic amine derivative of thepresent invention in organic thin film layers of the organic EL device,the obtained organic EL device can exhibit a long life and a highluminance of light emitted and a high efficiency of light emission.

The organic EL device of the present invention is suitably applied to,for example, surface light-emitting members such as a flat panel displayfor wall-type TV, light sources for copiers, printers, back light forliquid crystal displays and measuring equipments, display panels, markerlights, etc. Further, the material of the present invention can be usednot only for organic EL devices but also in other applications such aselectrophotographic members, photoelectric converters, solar cells,image sensors, etc.

The present invention will be described in more detail by reference tothe following examples. However, it should be noted that these examplesare only illustrative and not intended to limit the invention thereto.

SYNTHESIS EXAMPLE 1 Synthesis of Compound (6)

Under an argon flow, 6.0 g (10 mmol) of 2,6-di(1-adamantyl)anthracene,5.6 g (25 mmol) of 4-isopropylphenyl-p-tolylamine, 0.03 g (1.5 mol %) ofpalladium acetate, 0.06 g (3 mol %) of tri-t-butyl phosphine, 2.4 g (25mmol) of t-butoxy sodium and 100 mL of dried toluene were charged into a300 mL three-necked flask equipped with a condenser tube, and thenstirred under heating at 100° C. over night. After completion of thereaction, the precipitated crystals were separated from the reactionsolution by filtration, and then washed with 50 mL of toluene and 100 mLof methanol, thereby obtaining 7.2 g of a light-yellow powder. The thusobtained powder was subjected to NMR spectrum analysis (FIG. 1) andFD-MS (field desorption mass spectrum analysis). As a result, thereaction product was identified as the compound (6) (yield: 82%).

Meanwhile, the NMR spectrum was measured by Fourier-transform NMRanalyzer “R-1900” (90 MHz) available from Hitachi Limited, using CDCl₃as a solvent.

SYNTHESIS EXAMPLE 2 Synthesis of Compound (7)

Under an argon flow, 4.5 g (10 mmol) of 2,6-di-t-butyl anthracene, 5.2 g(25 mmol) of 4-isobutyl diphenyl amine, 0.03 g (1.5 mol %) of palladiumacetate, 0.06 g (3 mol %) of tri-t-butyl phosphine, 2.4 g (25 mmol) oft-butoxy sodium and 100 mL of dried toluene were charged into a 300 mLthree-necked flask equipped with a condenser tube, and then stirredunder heating at 100° C. over night. After completion of the reaction,the precipitated crystals were separated from the reaction solution byfiltration, and then washed with 50 mL of toluene and 100 mL ofmethanol, thereby obtaining 6.0 g of a light-yellow powder. The thusobtained powder was subjected to NMR spectrum analysis (FIG. 2) andFD-MS. As a result, the reaction product was identified as the compound(7) (yield: 85%). Meanwhile, the NMR spectrum was measured under thesame conditions as described in SYNTHESIS EXAMPLE 1.

SYNTHESIS EXAMPLE 3 Synthesis of Compound (8)

Under an argon flow, 4.5 g (10 mmol) of 2,6-di-t-butyl anthracene, 4.9 g(25 mmol) of p,p′-ditolylamine, 0.03 g (1.5 mol %) of palladium acetate,0.06 g (3 mol %) of tri-t-butyl phosphine, 2.4 g (25 mmol) of t-butoxysodium and 100 mL of dried toluene were charged into a 300 mLthree-necked flask equipped with a condenser tube, and then stirredunder heating at 100° C. over night. After completion of the reaction,the precipitated crystals were separated from the reaction solution byfiltration, and then washed with 50 mL of toluene and 100 mL ofmethanol, thereby obtaining 6.3 g of a light-yellow powder. The thusobtained powder was subjected to NMR spectrum analysis (FIG. 3) andFD-MS. As a result, the reaction product was identified as the compound(8) (yield: 93%). Meanwhile, the NMR spectrum was measured under thesame conditions as described in SYNTHESIS EXAMPLE 1.

SYNTHESIS EXAMPLE 4 Synthesis of Compound (9)

Under an argon flow, 4.5 g (10 mmol) of 2,6-di-t-butyl anthracene, 5.6 g(25 mmol) of 4-isopropylphenyl-p-tolylamine, 0.03 g (1.5 mol %) ofpalladium acetate, 0.06 g (3 mol %) of tri-t-butyl phosphine, 2.4 g (25mmol) of t-butoxy sodium and 100 mL of dried toluene were charged into a300 mL three-necked flask equipped with a condenser tube, and thenstirred under heating at 100° C. over night. After completion of thereaction, the precipitated crystals were separated from the reactionsolution by filtration, and then washed with 50 mL of toluene and 100 mLof methanol, thereby obtaining 7.0 g of a light-yellow powder. The thusobtained powder was subjected to NMR spectrum analysis (FIG. 4) andFD-MS. As a result, the reaction product was identified as the compound(9) (yield: 95%). Meanwhile, the NMR spectrum was measured under thesame conditions as described in SYNTHESIS EXAMPLE 1.

SYNTHESIS EXAMPLE 5 Synthesis of Compound (10)

Under an argon flow, 5.0 g (10 mmol) of 2.6-dicyclohexyl anthracene, 5.6g (25 mmol) of 4-isopropylphenyl-p-tolylamine, 0.03 g (1.5 mol %) ofpalladium acetate, 0.06 g (3 mol %) of tri-t-butyl phosphine, 2.4 g (25mmol) of t-butoxy sodium and 100 mL of dried toluene were charged into a300 mL three-necked flask equipped with a condenser tube, and thenstirred under heating at 100° C. over night. After completion of thereaction, the precipitated crystals were separated from the reactionsolution by filtration, and then washed with 50 mL of toluene and 100 mLof methanol, thereby obtaining 7.1 g of a light-yellow powder. The thusobtained powder was subjected to NMR spectrum analysis (FIG. 5) andFD-MS. As a result, the reaction product was identified as the compound(10) (yield: 90%). Meanwhile, the NMR spectrum was measured under thesame conditions as described in SYNTHESIS EXAMPLE 1.

SYNTHESIS EXAMPLE 6 Synthesis of Compound (11)

Under an argon flow, 5.0 g (10 mmol) of 2.6-dicyclohexyl anthracene, 6.7g (25 mmol) of 4-t-butylphenyl-4-isopropylphenyl amine, 0.03 g (1.5 mol%) of palladium acetate, 0.06 g (3 mol %) of tri-t-butyl phosphine, 2.4g (25 mmol) of t-butoxy sodium and 100 mL of dried toluene were chargedinto a 300 mL three-necked flask equipped with a condenser tube, andthen stirred under heating at 100° C. over night. After completion ofthe reaction, the precipitated crystals were separated from the reactionsolution by filtration, and then washed with 50 mL of toluene and 100 mLof methanol, thereby obtaining 8.3 g of a light-yellow powder. The thusobtained powder was subjected to NMR spectrum analysis (FIG. 6) andFD-MS. As a result, the reaction product was identified as the compound(11) (yield: 95%). Meanwhile, the NMR spectrum was measured under thesame conditions as described in SYNTHESIS EXAMPLE 1.

EXAMPLE 1

A 120 nm-thick transparent electrode made of indium oxide was formed ona glass substrate having a size of 25 mm×75 mm×1.1 mm. The glasssubstrate with the transparent electrode was cleaned by irradiation ofUV and ozone, and then mounted to a vacuum vapor deposition apparatus.

First,N′,N″-bis[4-(diphenylamino)phenyl]-N′,N″-diphenylbiphenyl-4,4′-diaminewas vapor-deposited to form a hole injecting layer having a thickness of60 nm, and then N,N,N′,N′-tetrakis(4-biphenyl)-4,4′-benzidine wasvapor-deposited on the hole injecting layer to form a hole transportinglayer having a thickness of 20 nm. Then,10,10′-bis[1,1′,4′,1″]terphenyl-2-yl-9,9′-bianthracenyl and the abovecompound (6) were simultaneously vapor-deposited at a weight ratio of40:3 on the hole transporting layer to form a light emitting layerhaving a thickness of 40 nm.

Next, tris(8-hydroxyquinolinato)aluminum was vapor-deposited on thelight emitting layer to form an electron injecting layer having athickness of 20 nm. Then, lithium fluoride and then aluminum weresuccessively vapor-deposited on the electron injecting layer to formlayers having thicknesses of 1 nm and 150 nm, respectively. The thusformed lithium fluoride/aluminum film was functioned as a cathode. As aresult, an organic EL device was produced.

When the thus obtained organic EL device was subjected to energizingtest, it was confirmed that a green light with an efficiency of lightemission of 20 cd/A and a luminance of light emission of 2011 cd/m²(light emission maximum wavelength: 530 nm) was emitted at a voltage of7.0 V and a current density of 10 mA/cm². Further, as a result ofsubjecting the device to a D.C. continuous energizing test at an initialluminance of 3000 cd/m², it was confirmed that the half life thereof was4500 h.

EXAMPLE 2

The same procedure as in EXAMPLE 1 was repeated except for using thecompound (9) in place of the compound (6), thereby producing an organicEL device.

When the thus obtained organic EL device was subjected to energizingtest, it was confirmed that a green light with an efficiency of lightemission of 19 cd/A and a luminance of light emission of 1914 cd/m²(light emission maximum wavelength: 527 nm) was emitted at a voltage of7.5 V and a current density of 10 mA/cm². Further, as a result ofsubjecting the device to a D.C. continuous energizing test by the samemethod as described in EXAMPLE 1, it was confirmed that the half lifethereof was 4000 h.

EXAMPLE 3

The same procedure as in EXAMPLE 1 was repeated except for using thecompound (10) in place of the compound (6), thereby producing an organicEL device.

When the thus obtained organic EL device was subjected to energizingtest, it was confirmed that a green light with an efficiency of lightemission of 22 cd/A and a luminance of light emission of 2201 cd/m²(light emission maximum wavelength: 529 nm) was emitted at a voltage of7.0 V and a current density of 10 mA/cm². Further, as a result ofsubjecting the device to a D.C. continuous energizing test by the samemethod as described in EXAMPLE 1, it was confirmed that the half lifethereof was 5000 h.

EXAMPLE 4

The same procedure as in EXAMPLE 1 was repeated except for using thecompound (11) in place of the compound (6), thereby producing an organicEL device.

When the thus obtained organic EL device was subjected to energizingtest, it was confirmed that a green light with an efficiency of lightemission of 24 cd/A and a luminance of light emission of 2411 cd/m²(light emission maximum wavelength: 529 nm) was emitted at a voltage of7.0 V and a current density of 10 mA/cm². Further, as a result ofsubjecting the device to a D.C. continuous energizing test by the samemethod as described in EXAMPLE 1, it was confirmed that the half lifethereof was 6000 h.

COMPARATIVE EXAMPLE 1

The same procedure as in EXAMPLE 1 was repeated except for using9,10-bis(diphenylamino)anthracene in place of the compound (6), therebyproducing an organic EL device.

When the thus obtained organic EL device was subjected to energizingtest, it was confirmed that a yellow light with an efficiency of lightemission of 9 cd/A and a luminance of light emission of 987 cd/m² (lightemission maximum wavelength: 555 nm) was emitted at a voltage of 6.8 Vand a current density of 10 mA/cm². Further, as a result of subjectingthe device to a D.C. continuous energizing test by the same method asdescribed in EXAMPLE 1, it was confirmed that the half life thereof wasas short as 1500 h.

COMPARATIVE EXAMPLE 2

The same procedure as in EXAMPLE 1 was repeated except for using2-methyl-9,10-bis(diphenylamino)anthracene in place of the compound (6),thereby producing an organic EL device.

When the thus obtained organic EL device was subjected to energizingtest, it was confirmed that a yellow light with an efficiency of lightemission of 8 cd/A and a luminance of light emission of 805 cd/m² (lightemission maximum wavelength: 558 nm) was emitted at a voltage of 6.8 Vand a current density of 10 mA/cm². Further, as a result of subjectingthe device to a D.C. continuous energizing test by the same method asdescribed in EXAMPLE 1, it was confirmed that the half life thereof wasas short as 700 h.

INDUSTRIAL APPLICABILITY

The organic EL device produced using the novel aromatic amine derivativeas a light emitting material according to the present invention canexhibit a practically sufficient luminance of light emitted even uponapplying a low voltage thereto, and has a high efficiency of lightemission, and is free from deterioration in properties even after beingused for a long period of time and, therefore, has a long life.Therefore, the organic EL device of the present invention has a highutility and is extremely useful as a light source for various electronicequipments.

1. An aromatic amine derivative represented by the following generalformula (1):

wherein A¹ and A² are each independently a hydrogen atom, a substitutedor unsubstituted alkyl group having 1 to 10 carbon atoms, a substitutedor unsubstituted aryl group having 5 to 50 nuclear carbon atoms, asubstituted or unsubstituted cycloalkyl group having 3 to 20 nuclearcarbon atoms, a substituted or unsubstituted alkoxy group having 1 to 10carbon atoms, a substituted or unsubstituted aryloxy group having 5 to50 nuclear carbon atoms, a substituted or unsubstituted arylamino grouphaving 5 to 50 nuclear carbon atoms, a substituted or unsubstitutedalkylamino group having 1 to 10 carbon atoms, or a halogen atom; p and qare each an integer of 1 to 5 and s is an integer of 1 to 9 wherein whenp or q is 2 or more, a plurality of A¹ or A² groups may be the same ordifferent and may be bonded to each other to form an saturated orunsaturated ring, with the proviso that both of A¹ and A² are notsimultaneously hydrogen atoms; R¹ is a substituted or unsubstitutedsecondary or tertiary alkyl group having 3 to 10 carbon atoms, or asubstituted or unsubstituted secondary or tertiary cycloalkyl grouphaving 3 to 10 carbon atoms; t is an integer of 1 to 9, and when t is 2or more, a plurality of R¹ groups may be the same or different; R² is ahydrogen atom, a substituted or unsubstituted alkyl group having 1 to 10carbon atoms, a substituted or unsubstituted aryl group having 5 to 50nuclear carbon atoms, a substituted or unsubstituted cycloalkyl grouphaving 3 to 20 nuclear carbon atoms, a substituted or unsubstitutedalkoxy group having 1 to 10 carbon atoms, a substituted or unsubstitutedaryloxy group having 5 to 50 nuclear carbon atoms, a substituted orunsubstituted arylamino group having 5 to 50 nuclear carbon atoms, asubstituted or unsubstituted alkylamino group having 1 to 10 carbonatoms, or a halogen atom; u is an integer of 0 to 8 and when u is 2 ormore, a plurality of R² groups may be the same or different; and a sumof s, t and u (s+t+u) is an integer of 2 to
 10. 2. The aromatic aminederivative according to claim 1, wherein said aromatic amine derivativeis represented by the following general formula (2):

wherein A¹, A², p, q, R¹ and R² are the same as defined above.
 3. Thearomatic amine derivative according to claim 1, wherein said aromaticamine derivative is represented by the following general formula (2-1):

wherein A¹, A², q, R¹ and R² are the same as defined above.
 4. Thearomatic amine derivative according to claim 1, wherein said aromaticamine derivative is represented by the following general formula (2-2):

wherein A¹, A², R¹ and R² are the same as defined above.
 5. The aromaticamine derivative according to claim 1, wherein said aromatic aminederivative is represented by the following general formula (2-3):

wherein A¹, A², R¹ and R² are the same as defined above.
 6. The aromaticamine derivative according to claim 1, wherein said aromatic aminederivative is represented by the following general formula (3):

wherein A¹, A², p, q, R¹ and R² are the same as defined above; and R³ isa hydrogen atom, a substituted or unsubstituted alkyl group having 1 to10 carbon atoms, a substituted or unsubstituted aryl group having 5 to50 nuclear carbon atoms, a substituted or unsubstituted cycloalkyl grouphaving 3 to 20 nuclear carbon atoms, a substituted or unsubstitutedalkoxy group having 1 to 10 carbon atoms, a substituted or unsubstitutedaryloxy group having 5 to 50 nuclear carbon atoms, a substituted orunsubstituted arylamino group having 5 to 50 nuclear carbon atoms, asubstituted or unsubstituted alkylamino group having 1 to 10 carbonatoms, or a halogen atom.
 7. The aromatic amine derivative according toclaim 1, wherein said aromatic amine derivative is represented by thefollowing general formula (4):

wherein A¹, A², p, q, R¹ and R² are the same as defined above; and R³and R⁴ are each independently a hydrogen atom, a substituted orunsubstituted alkyl group having 1 to 10 carbon atoms, a substituted orunsubstituted aryl group having 5 to 50 nuclear carbon atoms, asubstituted or unsubstituted cycloalkyl group having 3 to 20 nuclearcarbon atoms, a substituted or unsubstituted alkoxy group having 1 to 10carbon atoms, a substituted or unsubstituted aryloxy group having 5 to50 nuclear carbon atoms, a substituted or unsubstituted arylamino grouphaving 5 to 50 nuclear carbon atoms, a substituted or unsubstitutedalkylamino group having 1 to 10 carbon atoms, or a halogen atom.
 8. Thearomatic amine derivative according to claim 1, wherein said aromaticamine derivative is represented by the following general formula (5):

wherein A¹, A², p, q, R¹ and R² are the same as defined above; and R³ isa hydrogen atom, a substituted or unsubstituted alkyl group having 1 to10 carbon atoms, a substituted or unsubstituted aryl group having 5 to50 nuclear carbon atoms, a substituted or unsubstituted cycloalkyl grouphaving 3 to 20 nuclear carbon atoms, a substituted or unsubstitutedalkoxy group having 1 to 10 carbon atoms, a substituted or unsubstitutedaryloxy group having 5 to 50 nuclear carbon atoms, a substituted orunsubstituted arylamino group having 5 to 50 nuclear carbon atoms, asubstituted or unsubstituted alkylamino group having 1 to 10 carbonatoms, or a halogen atom.
 9. An organic electroluminescence devicecomprising a cathode, an anode and one or plural organic thin filmlayers having at least a light emitting layer which are sandwichedbetween the cathode and the anode, wherein at least one of the organicthin film layers contains the aromatic amine derivative as claimed inclaim 1 in the form of a single substance or a component of a mixture.10. The organic electroluminescence device according to claim 9, whereinthe light emitting layer contains the aromatic amine derivative.